Method of refrigeration



Qt.23,-1934. 'Y l RRBSS 1,977,919

METHOD OF REFRIGERATION Filed Aug. 14 1931 TTT# (nmub,"

A Eg Tw 9 "9 y j! [l l e "n, 1 f Z ,W l INVENToR.

B/q/J LL ATTORNEY;

-55 nexed drawing wherein:

Patented oo1.23,1934

UNITED STATES A P ATENT OFFICE s claims.

This invention relates to improvements in refrigeration, eitherindustrial or domestic,- and it has particular reference to a method orprocess lby which to prolong the state of change of water ice when usedas a refrigerant.

p The principal object Vof the invention resides in a method ofcombining water ice and solid carbon dioxide to lower the temperature ina given area and maintain the temperature uniform over a long period.The action of the water ice in passing from a solid to a liquid isprolonged for an indeflnite period of time, so long as solid carbondioxide is added.

The invention comprehends the provision of a new and useful method bywhich to improve the refrigeration of railway cars. Particularly inrailway fruit and vegetable cars it is necessary to maintain a settemperature at all times, when loaded, which necessitates the stoppingof the train at intervals to have additional ice placed in the bunkersof the cars. 'This is an expensive procedure as the equipment is lyingidle, train crews are idle and the running time is reduced. Theinvention affords a method by which to associate water ice with solidcarbon dioxide, both refrlgerants being placed in the bunkers of therefrigerator cars,. and ywill furnish satisfactory refrigeration forlonger periods and will therefore permit greater distances to betravelled before re-icing becomes necessary.

Still another object of the invention resides in the advantages to beobtained in commercial as well as domestic refrigeration by combiningthe solid carbon dioxide and water ice, by which it is possible to solocate frozen foods in the close vicinity of the solid carbon. dioxideand keep them in frozen state without reducing the temperature of theother parts of the refrigerator to such a degree as to be dangerous forlpreserving 40 other types of food. Moreover, the cost of service ismaterially reduced since many customers using water ice refrigerationare required to be served with ice daily and the present invention makesit possible to prolong refrigeration so that 45 service may be reducedto the very which results in a decrease in delivery cost whichrepresents approximately one-third of the retail price of water ice.

With the foregoing and other objects in view,

50 the invention has particular reference to the novel method ofassociating the refrigerants to bring about the objects set forth andwhich will become manifest as the description proceeds, and

as shown in one form of application in the anlties are arranged forshipment.

(ci. sz-91.5)

Figure 1 is a longitudinal section view of a railway car, also showingin section'the ice bunkers in which the refrigerants are associated.

Figure 2 is a plan view partly in section, showing the ice bunker at oneend and the covers at `0 the opposite end. Y

Figure 3 is a fragmentary viewin perspective showing the position of theice bunker in the end of the car andthe means by which the bunkers arelled. y

Figure 4 is a perspective view showing the carbon dioxide receptacle'.I

Continuing more in" detail with the drawing, 1 designates theconventional type of railway refrigerating car and showing in Figure 1the 70 conventional manner in which certain commodi- In practice,bunkers 2 are situated in either end of the car `and are lled throughopenings 3 in the top 4 of the car. These openings are pro- 75 videdwith covers 5. When hauling loads of perishable merchandise, care mustbe taken that the bunkers 2 are lled with water ice so as to insurecirculation of cold air throughout the car. Re-icing the bunkers must beclone4 frequently in 30 view of the fact that water ice quickly meltsand the refrigerating effects produced thereby accordingly decrease.

This same condition prevails in domestic refrigeration where it iscustomary in most cases to 35 re-ice the refrigerator daily. With theuse of the present invention, re-icing is required only a few times perweek, depending of course upon the condition of the ice-refrigerator.

It is a known fact that a large body of water` has a tendency tostabilize the climate in its vicinity.. This is due to the fact thatwater has the property of absorbing a large amount of both A sensibleand latent heat before a change of state takes place. By change ofstateiis meant the changing from a liquid to a solid or from a liquid`to a gas. Water likewise has the property of giving oi heat when thesurrounding air becomes colder than the water. When a suflicient numberof B'. t. u. of sensible heat are subStracted, the temperature of waterwill be lowered to 32. As the water reaches the temperature of 32-, 144p B. t. u. of latent heat must be substracted before the liquid isturned into a solid (water ice). Likewise in passing from a solid to aliquid, water ice absorbs 144 B. t. u. Water ice has a specific heat of.5 and has the property of absorbing additional heat.

In passing from the sona to the gaseous siate-11o at atmosphericpressure, carbon dioxide takes up 248 B. t. u. of heat energy per pound.

The specific heat of solid carbon dioxide at 109 F. is 0.31 B. t. u. perpound per degree F., that is in order to raise or lower the temperatureof one pound of solid carbon dioxide one degree F.- at 109 F., 0.31 B.t. u. of heat energy -has to be added to or taken from solid carbondioxide accordingly `as its temperature is to be raised or lowered. Inthe temperature interval between 109 F. and 32 F. the mean specific heatof the vapor is about 0.19 B. t. u. per pound. Therefore one pound ofcarbon dioxide vapor after subliming from the solid will absorb 0.19 B.t. u. for each degree rise in temperature betweenr 109 F. and 32 F.

Besides the refrigerating effect due to the change of state, there isthe additional refrigerating effect of 27 B. t. u. perpound at 32 F.equal to the amount of heat which the carbon dioxide vapor at 109 F.after subliming from the solid, absorbs in being warmed to 32 F.Therefore one pound of carbon dioxide absorbs 275 B. t. u. in changingfrom a solid at 109 F. to a gas at 32 F. 'Ihis is approximately equal totwice the amount of heat (144 B. t. u. per pound) absorbed byice meltingat 32 F., and, as this is often expressed, one pound of solid carbondioxide has approximately the same refrigerating effect at 32 F. as twopounds of water ice.

With special reference to ,the association of solid carbon dioxide andwater ice, from the foregoing itis evident that when solid carbondioxide is brought into contact with water ice, the water ice willabsorb the refrigerating effect produced by the solid carbon dioxide. Aslong as theratio of the water ice to solid carbon dioxide is suiiicientfor the water ice to absorb the refrigerating eiect of the solid carbondioxide, the surrounding air will be affected in temperature by theinuence of the water ice only.

Before describing the application of the invention for use in connectionwith railway refrigeration, certain tests will be defined and theresults given, so that a more comprehensive idea of the invention may behad.

The rst test embodied the use of a modern type of householdrefrigerator, having one inch of corkboard and one half inch of wood-texinsulation in the walls and one inch of wood-tex, one inch of balsamwood and one inch of cork-board in the bottom. The capacity of therefrigerator was one hundred pounds. A standard recording thermometerwas used for obtaining continuous readings and the accuracy of thethermometer was checked with a standard mercury type thermometer.

The refrigerator was first thoroughly cooled with charging it with onehundred pounds of wa- -ter ice and air, and allowing it to stand fortwentyfour hours.` The temperature immediately below the ice compartmentwas reduced to 42. The water ice was then removed and five pounds ofsolid carbon dioxide was supported in the upper part of the ice chamberon a card-board box. The temperature in the milk compartment dropped to38" in one hour and was maintained at this temperature for another hourand within approximately one and one-half hours longer the temperaturehad again become 42. In other;

words, ve pounds of solid carbon dioxide lowered the temperature of therefrigerator for a period of three-and one-half hours. The solid carbondioxide had entirely disappeared in approximately six hours.

A second test was made with 65 pounds of water ice in the icecompartment and ve pounds of solid carbon dioxide was wrapped in paperand placed directly on top of the water ice. perature in the milkcompartment was 44 at the time and in three hours it had dropped to 42and held this temperature until all of the solid carbon dioxide had beensublimated. There was no appreciable difference in the temperature ofthe refrigerator with the solid carbon dioxide inserted, but the waterice only melted 12% pounds during the next 17 hours, whereas with thewater ice alone it would have been twenty-five pounds.

In carrying out a third test with the temperature of the refrigerator at43, all of the water' ice was removed and ten pounds of solid carbondioxide was inserted, supported on a card-board box in the upper part ofthe ice chamber. In three hours the temperature dropped to 34 and fivehours laterthe temperature had returned to 43. 'I'he eect of the solidcarbon dioxide refrigeration was therefore totally lost in eight hours.

In a fourth test, 50 pounds of water ice was placed in the ice chamberwith ten pounds uf solid carbon dioxide placed on top of the water ice.The temperature of the refrigerator gradually increased to 44 and thesolid carbon dioxide was totally evaporated. During the twenty-fivehours following the insertion of the water ice and solid carbon dioxide,only seven pounds of water ice melted. I

In addition to the above tests, other tests were conducted with thesol-id carbon dioxide inclosed in a card-board container and with itthoroughly wrapped in paper, both of which are known to be good heatinsulators. The only difference that could be observed was that the rateof sublimation was greatly reduced without there being an appreciabledifference in the temperature of the refrigerator. A metal containerfilled with brine was placed in the ice compartment of the refrigerator.Within the brine solution another metal container was placed, containingve pounds of The temsolid carbon dioxide. A reduction of temperature ofthe refrigerator was obtained by this method.

The results of the above tests prove conclusively that combinations ofsolid carbon dioxide and water ice are an improvement in refrigeration.Air is cooled in any refrigerator only by coming in contact with acolder surface. When solid carbon dioxide is placed in contact with thewater ice, some of the heat units absorbed by the water ice from the airare transmitted by conduction to the solid carbon dioxide and thereabsorbed, causing it to sublimate. The air directly in contact with thesolid carbon dioxide also causes the carbon dioxide to sublimate. Therate of sublimation is somewhat retarded when the water ice is incontact with the solid carbon dioxide and the surrounding air is notappreciably lower in temperature due to the fact that water ice absorbsa great deal of the refrigerating effect of the lsolicl carbon dioxide.The actual temperature of theV air passing over the combination of solidcarbon dioxide and water ice is not especially lower than when the solidcarbon dioxide is not 1, ,91o 3 although further tests might prove aslight vari- These fins 9 conduct the irigidity oi the carbon ation inthis ratio. dioxide into the bunker 2.

The foregoing explanation, while quitein dtail, is intended to presentthe invention in the most comprehensive manner as applied to bothindustrial and domestic refrigeration, although the drawing illustratesthe-mode of application commercially in one form. The. association orrelationship oi' the carbon dioxide with the water ice is clearly shownin the drawing and corresponds quite clearly with the description givenin the four tests set out in the foregoing.

'I'he refrigerating car which is iced in the customary manner by llingthe bunkers 2 with water ice has a funnel-shaped receptacle 6 therein.shown in detail in Figure 4. This receptacle is lled with solid carbondioxide through the hoppers 7 at either side of the top of thereceptacle 6. The hoppers "lare arranged so that when opened in themanner shown in Figure 4, a chute is provided for convenience incharging the receptacle 6. A gas relief valve 8 is provided for thecarbon dioxide receptacle 6 to allow for the escape of sublimatinggases.

It has been stated previously that the water ice has a tendency toabsorb the eil'ects of the solid carbon dioxide and in so doing, thetemperature within the car 1 remains xed a longer period of time than ifwater ice alone were used.

the solid carbon dioxide preserving the water ice for longer periods oftime. The fact that the water ice absorbs the effects of the carbondioxide prevents the temperature from being lowered to a point where itwould be detrimental upon the merchandise within the car.

Y In order to further lend to the preserving effect of the carbondioxide upon the water ice, ns 9 are provided on the sides of thereceptacle 6.

While the invention has been described in great particularity, it isunderstood that it is not intended that the same shall be hunted to thespecific details depended upon for the description thereof in theforegoing, and lthat certain' alterations and modifications may be madewhich may fall within the category of its objectsk as set forth in thefollowing claims therefor.

What is claimed is:

1. The method of refrigeration which comprises placing a body of carbondioxide ice adjacent an air space to be refrigerated, placing a body ofvwater ice between said carbon dioxide ice and said spacev and inthermal contact with said carbon dioxide ice, exposing a surface of thewater ice to thermal contact with the air in said space, andproportioning the relative quantities of the two refrigerante so as tolprolong the refrigerating eifeet of said water. ice but not tomaterially reduce the temperature of said exposed surface.

2. In a refrigerator as described, the combina- `tion with a refrigerantcabinet, of means for

